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Re: [TenTec] Omni Vl Plus Amplifier Switching

To: tentec@contesting.com
Subject: Re: [TenTec] Omni Vl Plus Amplifier Switching
From: Bob McGraw K4TAX <rmcgraw@blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 27 Mar 2020 10:41:27 -0500
List-post: <mailto:tentec@contesting.com>
Barry et al:

To the best of my knowledge, having owned 2 of the Tentec Omni VI Plus transceivers, there is no RF delay upon key closure.   Thus the radio is designed to work in QSK mode with the Tentec series of amplifiers.  Thus the delay is effectively incorporated in the amplifier.  This then places the delay in the TX EN line.

As to using the KPA500, and I have one of those on the desk, some form of keying and timing will be required such that the amp is keyed first and then the Omni VII Plus is keyed.    This of course will cause a delay of some small amount in your keying.  That may be operational problematic depending on the amount of delay and would not likely be satisfactory in operating QSK.

There is a short delay of about 10 milliseconds which does occur on the Control Board.  See page 4-16, paragraph 3, in the manual. This delay is available on the keying loop.  Personally, I would carefully measure the timing from key closure to RF generation to make sure the 10 ms is indeed present.  If so that is most likely adequate to switch the KPA500.  Even so, some interface switching arrangement is needed.

A friend of mine is using an external keyer which does provide keying output for the amplifier and adjustable delayed output to key the radio.  I think it is an old MFJ product.    Even then, he removed the internal relay and converted the circuit to a open collector circuit.

I suggest buying a Tentec amp, Centurion or Titian, and be done with it.

73

Bob, K4TAX


On 3/26/2020 9:54 PM, Barry Simpson wrote:
After a two year search, I have finally acquired a very nice Omni Vl Plus.

I would like to know if anyone has designed/undertaken a modification to
eliminate the slow noisy amplifier relay to allow solid state QSK switching
of an external amplifier.

I know that the Omni has the keying in/out function that fulfils the keying
role with Ten Tec and other amplifiers with the same keying in/out
circuitry. However, I want to control an Elecraft KPA500 which does not
have the in/out function.

I look forward to any responses.

Regards and 73 to all at this difficult time.

Barry Simpson  VK2BJ
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